We're talkin' about the Icehouse game system. It's like a 21st century set of playing cards, as designed by Egyptian pharaohs from the distant future. And it's open source... sorta.
Quick question: Who holds the intellectual property rights to poker? Gin rummy? Spades? Nobody, that's who. These games can be played with any common set of playing cards -- and these games are just a handful of the possibilities open to anyone with a basic 54 card deck. This philosophy is what influenced game maker Looney Labs -- the same guys who created the geek favorite card game Fluxx -- to develop the Icehouse game system. It's like a 21st century set of playing cards, as designed by Egyptian pharaohs from the distant future.
The Icehouse game system uses trios of colored pyramids that stack atop one another. Each color gets a small, medium, and large pyramid, and using various sets of these playing pieces unlocks dozens of potential games. For the beginners, there's Treehouse; for seasoned players, there's Rotationary; and for the hardcore, there's Martian Chess, as shown above. More to the point, there's nothing stopping you (or anyone) for dreaming up new games using these basic tools. So, Linux fanatics, I expect Martian Chess to be a staple at the next Penguicon. Any other board game would be hypocritical.
(Found via io9.)